Sauté the Aromatics: In a large pot, heat 2 tbsp olive oil over medium heat. Add 1 diced onion and cook for 4-5 minutes until it becomes translucent. Next, stir in 3 minced garlic cloves, 1.5 tsp chili powder, 1 tsp cumin, 0.5 tsp smoked paprika, 0.5 tsp oregano, and a pinch of salt & pepper. Cook until fragrant, about an additional minute.
Build the Soup Base: Pour in 4 cups chicken broth, followed by 15 oz red enchilada sauce and 14.5 oz fire-roasted diced tomatoes. Stir to combine and then add 15 oz black beans (drained), 1 cup corn, and 2 cups shredded cooked chicken. Bring the mixture to a gentle boil.
Simmer the Soup: Once boiling, lower the heat, cover, and let the soup simmer for 20 minutes, stirring occasionally. Taste and adjust the seasonings as necessary!
Thicken the Soup: In a small bowl, mix 2 tbsp masa harina with 2 tbsp water to form a slurry. Add this slurry to the soup and simmer for another 5 minutes until the soup thickens.
Add Cheese and Cream: Gradually stir in 1 cup shredded Mexican cheese blend and the optional 0.5 cup heavy cream until melted and incorporated for a rich finish.
Serve and Garnish: Ladle the soup into bowls and let your creativity shine with toppings! Consider adding tortilla chips, diced avocado, sour cream, and a sprinkle of fresh cilantro. Serve with lime wedges for an extra zest.